I. Field of the Invention
This invention relates generally to signature distributing pockets or hoppers used in high speed bindery equipment, and more particularly to an improved pocket or hopper incorporating a means for preventing the scuffing or marring of printed sheets being fed by such a pocket onto the bindery line conveyor.
II. Discussion of the Prior Art
In a so-called "demographic binder" for magazines and the like, it is possible to custom design the contents of the magazine intended to reach a particular customer or class of customers. Thus, for example, if the marketing department of a major automobile manufacturing company determines from its records that a particular individual customarily purchases a new automobile about every 30 months, in a computer controlled magazine bindery line, it is possible to insure that this particular subscriber will receive a magazine which will include an advertisement for its car product.
A demographic binder gathering section typically includes a large plurality of hoppers or pockets whose signature contents are used to assemble a magazine on a conveyor passing beneath such pockets. In a non-demographic mode, each pocket will deliver a signature to each magazine. In a demographic mode, however, a pocket will deliver a signature only if the specific magazine then passing beneath it is intended to have that particular signature. If that signature is not scheduled to be deposited on the magazine being assembled as it passes beneath that given pocket, no signature is fed at that station as the book progresses along the gathering conveyor.
The existing binder pockets in common use, particularly those manufactured by A.M. Graphics Corporation Model No. RG-318A, embody a two-part dispensing operation. The first part consists of a rotating separator disc that cycles each time that a potential signature transfer could take place. The second part is a vacuum device called a "sucker bar" that functions or not, depending upon whether a signature is to be added to the magazine or omitted.
During each rotation of the separator disc, it touches the bottom of the next signature to be fed and rubs against it. In a non-demographic situation, this is not a problem because, typically, the separator disc will rub against the bottom sheet only once before it is delivered to the magazine being assembled on the underlying conveyor. However, in the case of a demographic printing line, it is possible that many rotations of the separator disc may take place before a given page is withdrawn from its pocket or hopper. It has been found that the repeated rubbing of the rotating separator disc with the bottom of the signature next to be dispensed can abrade that surface, rendering it unsightly and unacceptable by the magazine publisher. It is this problem that the present invention addresses.